Round back spring binder

ABSTRACT

A round back spring binder having spring clamp elements formed with intersecting end portions which have to be spread apart in order to assemble the spring clamp elements into the binder, thereby pre-loading the back of the binder with an initial spring bias. When spread apart, the end portions of the spring clamp elements are angled toward a common line which is centered with respect to the back of the binder.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to spring back loose leaf binders.

2. Description of the Prior Art

The closest prior patent art known to applicant consists of thefollowing U.S. Pat. Nos.:

210,193

664,544

755,380

1,347,342

2,229,936

2,607,351

2,729,835

2,731,967

2,906,268

In addition to the above-cited prior art, is a practice in the industry(e.g., by applicant) of constructing spring back binders withasymmetrical springs in order to attain a preload condition. This priorart practice is illustrated in FIGS. 1, 2 and 2A of the drawing. Asidefrom the fact that the resultant pre-load is minimal -- sometimesentirely lacking -- this practice produces a disaligned binder which hasthe appearance of being defective.

Another practice in the industry is to construct spring back binderswith symmetrical springs and to provide an inner folder for the binderwhich fills the gap between the opposing ends of the springs. FIG. 2B ofthe drawing shows a typical symmetrical spring wherein the spring armsfocus upon a common line. However, it has not been found feasible tomaintain the ends of the arms in contact with each other. The result isa balanced spring but with a gap between the ends of the arms. Bydefinition, this precludes an initial or pre-load condition and, as hasabove been stated, this gap is sometimes filled by means of a folderwhich is placed within the binder.

SUMMARY OF THE INVENTION

This invention provides a spring back binder having symmetrical springelements with a positive preload which enables it to grip minimal leafthicknesses securely. The principle of the invention resides in the useof spring elements having intersecting and bypassing arms which must bespread apart when assembled into the binder. Spreading the spring armsapart impresses a spring bias upon the back of the binder and provides afunctionally adequate preload condition.

As is shown in the drawing, there are different ways of providingintersecting and bypassing spring arms. One way is to forminterdigitated fingers on the spring arms; another way is to notch thearms at alternate locations; and a third way is to form the arms alongparallel, diagonal lines. In each case, the spring arms symmetricallybypass each other. In order to assemble these springs into the binder itis necessary to spread their arms apart to the point where they are nolonger intersecting. This impresses a preload on the springs whichenables the binder to grip small numbers of relatively thin loose leafsheets, even a single such sheet. Moreover, the springs remain at alltimes symmetrical and this gives the binder a symmetrical appearance.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a round back spring binder made inaccordance with the prior art.

FIG. 2 is a section on the line 2--2 of FIG. 1.

FIG. 2A is a perspective view of a typical asymmetrical clamp springelement used in said prior art binder.

FIG. 2B is a perspective view of a typical symmetrical clamp springelement which is used in some prior art binders.

FIG. 3 is a perspective view of a round back spring binder made inaccordance with one form of this invention.

FIG. 4 is a top view of said binder with its outer covering removed toshow the construction thereof, partially in cross-section.

FIG. 5 is a section on the line 5--5 of FIG. 3.

FIG. 6 is an end view of the clamp spring element which is used in theconstruction of the binder which is illustrated in FIGS. 3, 4 and 5.

FIG. 7 is a front view of said clamp spring element looking in thedirection of arrows 7,7 of FIG. 6.

FIG. 8 is a plan view of the blank from which the said spring clampelement is made.

FIG. 9 is an end view of said spring clamp element, similar to that ofFIG. 6, except that it is spread apart preparatory to being assembledinto the binder.

FIG. 10 is an end view of a spring clamp element made in accordance witha second form of this invention.

FIG. 11 is a front view thereof looking in the direction of arrows 11,11of FIG. 10.

FIG. 12 is a plan view of a blank from which the spring clamp element ofFIGS. 10 & 11 is made.

FIG. 13 is an end view of said spring clamp element, similar to that ofFIG. 10, but showing it spread apart preparatory to being assembled intothe binder.

FIG. 14 is an end view of a spring clamp element made in accordance witha third form of this invention.

FIG. 15 is a front view of said spring clamp element, looking in thedirection of arrows 15,15 of FIG. 14.

FIG. 16 is a plan view of a blank from which the spring clamp element ofFIGS. 14 and 15.

FIG. 17 is an end view of said spring clamp element, similar to that ofFIG. 14, but showing it spread apart preparatory to it being assembledinto the binder.

DESCRIPTION OF PREFERRED EMBODIMENTS OF INVENTION

Referring to the first instance to one form of prior art as presentlypracticed in the industry, and to FIGS. 1, 2 and 2A of the drawing, itwill be observed that conventional round back spring binder 10 comprisesa pair cover panels 12 and 14, a spring back 16, and hinge means 18 ishingedly attaching the cover panels to the spring back. What issignificant in this conventional construction is that arms 20 and 22 ofthe spring clamp elements are asymmetrically disposed relative to eachother in that their respective ends fail to meet along the clamping lineof the binder. Instead, arm 20 is bent at a tighter angle relative tothe yoke of the spring than is arm 22. Consequently, arm 22 tends tooverlap arm 20, causing a misalignment in the cover panels of thebinder.

The reason for this asymmetrical construction is that it impresses apreload on the spring element for the intended purpose of enabling thebinder to grip relatively few sheets of loose leaf material. However,this purpose is not always attained and there is an inherent visibledisadvantage in the construction, namely, the misalignment of the coverpanels. This is evident from FIG. 2 of the drawing in which it is shownthat one cover panel 14 extends beyond the other cover panel 12.Although this construction is highly undesirable it is neverthelesscustomarily used in the industry for want of a better, commerciallyfeasible construction wherein a preload condition is attained. As hasbeen stated, the use of symmetrical or balanced springs (see FIG. 2B)does not produce the desired pre-load condition.

Referring now to the first embodiment of the present invention asillustrated in FIGS. 3-9 of the drawing, it will be observed that roundback spring binder 30 consists of the following component parts: a backmember 32 having a curved back section 34 and a pair of side sections 36and 38 extending from said curved back section, a pair of cover panels40 and 42, and a plurality of spring clamp elements 44 which areassembled with said back member 32 and provide the spring clampingaction of the binder. Back member 32 may be made in various ways but, inthe conventional practice, it comprises the following elements: an innerlayer 46 of fabric or other suitable sheet material, a pair ofintermediate layers 48 and 49 made of fiber sheets or heavy paperboardsor the like and an outer layer 50 of sheet material suited for thecovering of binders, albums and the like. The inner fabric layer 46 isalso attached to the cover panels and it functions as a hinge betweenthe back 32 and the two cover panels 40 and 42. Outer layer 50 alsocovers the cover panels and, like the inner fabric layer 46, itfunctions as a hinging element between the back and the covers of thebinder.

Another pair of elements in the assembly is a pair of metal stiffenerstrips 52 which are secured to and between the two intermediate layers48 and 49. Stiffener strips 52 perform two important functions, namely,they provide the back of the binder with adequate rigidity and theyfunction as anchorages for the spring clamp elements 44. As FIG. 4clearly shows, there are three such spring clamp elements in theillustrated binder and it will be understood that these spring clampelements are attached to the metal stiffener strips by spring pressureand to the intermediate fiber layer 49 by adhesive.

Turning now to the details of spring clamp element 44 as illustrated inFIGS. 6-9, it will be noted that it comprises a curved yoke 54 and apair of arms 56 and 58 extending from said yoke. Yoke 54 of each of thethree spring clamp elements 44 corresponds to curved back section 34 andarms 56, 58 correspond to side sections 36, 38. Spring clamp element 44is made from a blank 60 which has a generally rectangular shape formedwith a pair of laterally spaced fingers 62, 64 at one end thereof and acentrally disposed finger 66 formed at the opposite end thereof. Whenblank 60 is bent and formed to the shape of spring clamp element 44,arms 56 and 58 intersect, their respective fingers 62, 64 and 66assuming an interdigitated relationship. Spring clamp element 44 is madeof spring steel and it is this intersecting formation that impresses apreload upon the spring clamp element when its arms 56, 58 are spreadapart for installation into the binder. See FIG. 9. The principle ofthis invention resides in the fact that the bend 68 between yoke 54 andarms 56, 58 may be tightened (radius reduced) in excess of thecorresponding bend of the prior art as illustrated in FIGS. 1 and 2.This results from the intersecting and bypassing relationship betweenthe arms in their relaxed or untensioned state. Since it is necessary toflex the structure (mainly yoke 54) in order to attain the installationconfiguration shown in FIG. 9, the structure is placed under tensionsufficient to enable the binder to grip relatively few sheets oflooseleaf material.

The binder construction is in other respects conventional. Thus, thecover panels 40 and 42 include relatively stiff paperboard or cardboardcores 70 and it will be observed that covering material 50 covers notonly the back portion 32 but also the cover panels, forming a continuouscovering extending over the entire binder.

Reference to the second form of this invention as illustrated in FIGS.10-15, it will be understood that spring element 74 performs the samefunction in the binder as spring element 44 above described. The binderconstruction is in all respects similar to the construction abovedescribed; only the spring element is different. The principle alsoremains the same in that spring element 74 has a pair of intersectingarms 76, 78 extending from a bowed yoke 80. Arms 76 and 78 areintersecting because of the tight bend along bend lines 82. Arms 76 and78 are capable of intersecting because they are provided with laterallyoffset end portions 84 and 86. These laterally offset end portions areclearly shown in FIGS. 10 and 11 and in the plan view of blank 88 (FIG.12) from which the spring element 74 is made. In this form of theinvention, as in the first form, the intersecting arms must be spreadapart for assembly of the spring element into the binder. Spreading themapart produces the preload condition necessary to enable the binder togrip relatively few sheets of looseleaf material. The installation ofspring element 74 into the binder is the same as previously describedwith respect to spring element 44. The arms of spring element 74 aresecured to the stiffener strips of the binder and it is through thesestiffener strips that the three spring elements in the binder areenabled to cooperate in biasing the binder.

The third form of the invention is illustrated in FIGS. 14-17 of thedrawing. There, spring element 90 comprises a bowed yoke 92 and a pairof arms 94 and 96 extending from said bowed yoke along bend lines 98.The angles defined by bends 98 are relatively small in relation to thecorresponding angles of the prior art as shown in FIGS. 1 and 2. Arms 94and 96 extend angularly from bend lines 98 and thereby assume diagonalpositions in side by side relationship, one arm pointing in onedirection, the other arm pointing in the opposite direction, and the twoarms being thereby enabled to intersect as shown in FIG. 14 of thedrawing.

As FIG. 16 clearly shows blank 100 from which spring element 90 is madeis a four sided figure having parallel sides 102 and parallel ends 104.There are no notches or fingers at the ends of this blank. Instead ofinterdigitating its ends (as is the case with spring elements 44 and 74)spring element 90 is formed in substantially helical configuration, thearms disposed in parallel bypassing relation to each other. It is thisbypassing relationship which corresponds to the intersectingrelationship of the arms of spring elements 44 and 74, and which makesit possible to preload said spring element 90 when its arms are spreadapart for assembly into the binder. See FIG. 17.

The foregoing is a description of preferred embodiments of the inventionand it will be understood that they are intended to illustrate, notlimit, the invention. The scope of the invention is limited only by thelimitation of the appended claims. For example, the stiffener strips maybe made of suitable strip material other than the above-mentioned metal,and they may be attached by any conventional means other than theabove-mentioned adhesive means.

I claim:
 1. A round back spring binder comprising:(a) a back memberhaving a curved back section, a pair of side sections extendingtherefrom, and a pair of stiffener strips on said side sections, (b) apair of cover panels hingedly connected to said side sections, and (c)spring clamp elements mounted on said back member and operating betweenits back and side sections, (d) said spring clamp elements comprising acurved spring yoke and a pair of arms extending integrally therefrom,said arms being secured to said stiffener strips, (e) said integral armsof the spring clamp elements having laterally offset end portions andsaid spring yoke of the spring clamp elements being bowed to bias saidintegral arms toward each other such that their offset end portions arenormally held in intersecting relationship, (f) said integral arms ofthe spring clamp elements, when secured to the stiffener strips, beingspread apart against the tension in the bowed spring yoke, (g) therebyimparting a spring bias in the back member of the binder sufficient tohold its side sections in tensioned engagement with each other prior toplacement of insert material between them, and sufficient to enable saidside sections to tensionally engage and hold insert material placedbetween them.
 2. A round back spring binder in accordance with claim 1,wherein:(a) the intersecting offset end portions of the arms of thespring clamp elements comprise interdigitated fingers, (b) at least onesuch finger centered on one such arm, (c) at least two such fingersspaced on the other arm to accommodate the first mentioned fingerbetween them.
 3. A round back spring binder in accordance with claim 1,wherein:(a) the intersecting offset end portions of the arms of thespring clamp elements comprise a pair of offset fingers, (b) one suchfinger on one side of one of said arms, the other finger on the oppositeside of the other of said arms, (c) whereby said fingers are positionedto bypass each other in intersecting relationship.
 4. A round backspring binder in accordance with claim 1, wherein:(a) the arms of thespring clamp elements extend diagonally in opposite directions from thecurved yoke, (b) whereby the end portions of said arms are positioned tobypass each other in intersecting relationship.
 5. A round back springbinder in accordance with claim 1, wherein:(a) the cover panels arehingedly connected to the side sections of the back member by means of acontinuous flexible sheet, (b) said flexible sheet being secured to thecurved back and side sections of the back member, and being also securedto the two cover panels.
 6. A round back spring binder in accordancewith claim 5, wherein:(a) the flexible sheet comprises a sheet offabric, and (b) said sheet of fabric is adhesively secured to the innersurfaces of the curved back and side sections of the back member and theinner surfaces of the cover panels.
 7. A round back spring binder inaccordance with claim 6, wherein:(a) additional hinging means isprovided between the side sections of the back member and the coverpanels, (b) said additional hinging means comprising sheet materialwhich is adhesively secured to the outer surfaces of the curved back andside sections of the back member and the outer surfaces of the coverpanels, (c) said sheet material constituting the outer covering of saidback member and said cover panels.